US EPA ~ APPROVED TOTAL MAXIMUM DAILY LOAD (TMDL) FOR THE ANIMAS RIVER WATERSHED [SAN JUAN RIVER TO SOUTHERN UTE INDIAN TRIBE BND] SEPTEMBER 30, 2013 THIS PAGE LEFT INTENTIONALLY BLANK. i TABLE OF CONTENTS LIST OF TABLES ....................................................................................................................................... iv LIST OF FIGURES .................................................................................................................................... iv LIST OF EQUATIONS ............................................................................................................................... iv LIST OF ABBREVIATIONS ....................................................................................................................... v EXECUTIVE SUMMARY ......................................................................................................................... 2 INTRODUCTION ........................................................................................................................................ 5 1.0 SAN JUAN RIVER BASIN BACKGROUND .................................................................................... 5 1.1 Description and Land Ownership ................................................................................................. 5 1.2 Geology ........................................................................................................................................ 6 1.3 Water Quality Standards ............................................................................................................... 8 2.0 INTENSIVE WATER QUALITY SURVEY ..................................................................................... 10 2.1 Survey Design ............................................................................................................................. 10 2.2 Hydrologic Conditions ............................................................................................................... 11 3.0 INDIVIDUAL WATERSHED DESCRIPTIONS & IMPAIRMENTS ............................................. 13 3.1 Animas River Watershed (HUC 14080104) ............................................................................... 13 TOTAL MAXIMUM DAILY LOADS ...................................................................................................... 16 4.0 BACTERIA ........................................................................................................................................ 16 4.1 Target Loading Capacity ............................................................................................................ 16 4.2 Flow ............................................................................................................................................ 16 4.3 Calculations ................................................................................................................................ 18 4.4 Waste Load Allocations and Load Allocations .......................................................................... 19 4.4.1 Waste Load Allocation ......................................................................................................... 19 4.4.2 Load Allocation .................................................................................................................... 21 4.5 Identification and Description of Pollutant Source(s) ................................................................ 22 4.6 Linkage of Water Quality and Pollutant Sources ....................................................................... 24 4.7 Margin of Safety (MOS) ............................................................................................................. 25 4.8 Consideration of Seasonal Variation .......................................................................................... 25 4.9 Future Growth ............................................................................................................................. 25 5.0 TEMPERATURE ............................................................................................................................... 28 5.1 Target Loading Capacity ............................................................................................................ 28 5.2 Flow ............................................................................................................................................ 29 5.3 Calculations ................................................................................................................................ 30 5.3.1 Model Assumptions ............................................................................................................. 30 5.4 Waste Load Allocations and Load Allocations .......................................................................... 31 5.4.1 Waste Load Allocation ......................................................................................................... 31 5.4.2 Load Allocation .................................................................................................................... 33 ii 5.5 Identification and Description of Pollutant Source(s) ................................................................ 36 5.6 Linkage of Water Quality and Pollutant Sources ....................................................................... 37 5.7 Margin of Safety (MOS) ............................................................................................................. 40 5.8 Consideration of Seasonal Variation .......................................................................................... 41 5.9 Future Growth ............................................................................................................................. 41 6.0 TOTAL PHOSPHORUS .................................................................................................................... 43 6.1 Target Loading Capacity ............................................................................................................ 43 6.2 Flow ............................................................................................................................................ 43 6.3 Calculations ................................................................................................................................ 44 6.4 Waste Load Allocations and Load Allocations .......................................................................... 45 6.4.1 Waste Load Allocation ......................................................................................................... 45 6.4.2 Load Allocation .................................................................................................................... 46 6.4.3 TMDL Calculation ............................................................................................................... 46 6.5 Identification and Description of Pollutant Sources ................................................................... 47 6.6 Linkage between Water Quality and Pollutant Sources ............................................................. 48 6.7 Margin of Safety (MOS) ............................................................................................................. 50 6.8 Consideration of Seasonal Variability ........................................................................................ 50 6.9 Future Growth ............................................................................................................................. 50 7.0 Monitoring Plan .................................................................................................................................. 52 8.0 Implementation of TMDLs ................................................................................................................. 54 8.1 Point Sources – NPDES Permitting ............................................................................................ 54 8.1.1 E. coli ................................................................................................................................... 54 8.1.2 Temperature ......................................................................................................................... 54 8.1.3 Total Phosphorus .................................................................................................................. 55 8.2 Nonpoint Sources – WBP and BMP Coordination ..................................................................... 55 8.3 Clean Water Act §319(h) Funding ............................................................................................. 56 8.4 Other Funding Opportunities and Restoration Efforts in the San Juan River Basin................... 56 9.0 Applicable Regulations and Stakeholder Assurances ......................................................................... 57 10.0 Public Participation ............................................................................................................................. 59 11.0 References ........................................................................................................................................... 60 APPENDIX A. Conversion Factor Derivations ......................................................................................... 64 APPENDIX B. Source Documentation Sheet and Sources ......................................................................